Method of making elemental sulphur from ores and gaes containing sulphur



Oct. 3l, 1939. G, GAFI-HER 2.177.707

METHOD OF MAKING ELEMENTAL SULPHUR FROM GRES AND GASES CONTAININGSULPHUR Filed May 8, 1939 /Vaz (03 SOL 0770A /Vaz 505 .Sanna/v [V4/90mmms f3 45 Alva 0mm den (0 r.'

Patented oef. 31, 1939 y. UNITED STATE.

f 24uur* METHOD F MAKING ELEMENTAL SULPHUR e FROM'.'VV ORES AND GASES`CONTAININGii 5 .'1"

SULPHUR 1 Claim.

. rlihis disc'overyvrelates to the production of elemental sulphurvobtained from ores and gases containing sulphur.

This application is the continuation inV part of application No.189,131.

lution with `the sodium sulphide.

I have discovered an improvement in the method `of vproducing elementalsulphur from the method disclosed in my Patent No. 2,163,554, issuedJune 20, 1939, consists of the following:

The rst improvement is the elimination of the barium sulphite-bariumsulphide cycle.

It" has` been discovered in plant practice that by neutralizing the'acidsodiumsulphite formed in the first chamber of the bubble tank, shown inmy application,` 189,131, in a separate neutralicing tank using sodiumcarbonatesolution for the purpose until completely neutralized sodiumsulphite is formed, can be utilized after evaporating of water from thesolution to give normal sodium sulphite salt. Instead of bariumsulphite,

this normal sodium sulphite in this new and improved process is mixedwith carbon and put through the reduction furnace, reducing it to sodiumsulphide. By this step the waste of the insoluble barium salts notalways reduced to barium sulphide is eliminated, because any of thesodium sulphite not completely reduced in the furnace to sodium sulphideis still left in a soluble form and when the solution is made of thesodium sulphide the unreduced sodium compounds go into the so- This willbecome a constant (being a very small per cent) of a definite amount ineither process for no reduction furnace will reduce either bariumsulphite or sodium sulphite to the corresponding sulphides one hundredpercent. The solution of sodium sulphide containing a small constant percent of unreduced sodium` compound is carried to the head of thereaction chambers and through the process. These unreduced compounds arenot acted upon in either the carbonating or sulphiting chambers and comethrough to the reduction furnace again where they will have their chanceto be reduced, thus preserving for the cycle the sodium radical whichsmall amount in the barium process is lost through insolubility. Thisimprovement eliminates one extra compound and lessens the weight of `theburden through the process because barium `is many times heavier thansodium.

In addition another improvement over the one chamber to anotheruntillbyA tests the reactions desired to occurineachechamber-shall havebeen completed. e f Y e i The figures on the drawing showthe direction`of flowof the variousele'ments and arefdescribed as follows? 5 Sulphideore (preferably powderedlfis'introduced into the combustion" chamber "I'where it is burned, with the proper amount of; air, vto sulphur dioxide,SO2. If thel'fsl'llphidetoi'eTllSed is pylte`, the `reaction is:2FeS2"-|-1l0- Fe`2O'3`-l-4SO2. The metallic oxide (lilezOill isiremovedA'fromthe `bottom, andthe SO2 passes into't'hefprocess through pipe 2.This gas passes" through the waste heat" `boiler 3 which generates steamforfthel operation of the turbine generator l which produces electriccurrent for running the various pumps, conveyors,

etc., in the process. 'I'he exhaust steam from the turbine generator.passes into' the evaporators 5 for removing the -water from the sodiumsulphite solution thus forming the dry sodium sulphite ready forreduction (with the `addition of carbon) to sodium sulphide.

A part of the sulphur .dioxide passes into the conversion system, whichis composed of 6 compartments, 3 for sodium carbonate solution(l-af-bc), and 3 for sodium sulphide solution la-b-c. The SO2 passesinto 6--a, where the following chemical reactions take place:

The gas, then mostlyv carbon dioxide, CO2, passes into Ali--b, which isused `as a guard chamber to prevent any unconverted SO2 from passinginto the sodium sulphide solution. The gas, CO2, then passesinto thesodium sulphide chamber 'I-a, where the following conversion takesplace, liberating hydrogen sulphide, as follows:

(This chamber is preferably heated to prevent formation of bicarbonate.)This gas (hydrogen sulphide) passes through chamber 'l-b (also a guardchamber) and from there passes over into the sulphur chamber 8.(Chambers G-c and 'l-c are used as reserves, while refilling thesaturated chambers.) Sulphur dioxide from the main supply 2 is alsopassed into the sulphur chamber 9 where it is combined with the hydrogensulphide in the formation of sulphur and water, thus:

SO2+2H2S 2H2O+3S The sulphur is removed from this chamber. The sodiumsulphide supply tank is shown at 9 and supplies chambers '1 -a, l-b, and1c. As the sulphide is converted into carbonate in chambers l-af--b-c aspreviously shown, it is transferred as needed to chambers B-a--b-cwhere, as shown above, the carbonate solution is converted into sodiumsulphite, also into sodium bisulphite, NaI-ISGS. Finally, the bisulphiteis run into the neutralizing tank I Where it is converted into thenormal sulphite (NazSOs) by the introduction of sodium carbonate fromtank I I.

The CO2 given off from this passes into the auxiliary tank I2 containingsodium sulphide from the main supply tank 9, and H25 is given off Whichgoes into the main HzS supply,' and into the sulphur tank 8. The sodiumcarbonate formed in tank I 2 is the supply for tank I I. The

sodium sulphite solution from tank I0 passes into the evaporators anddriers and the dry sulphite is transferred on conveyor I3 Wheretheproper amount of carbon (coke) is added from bin I 4 for the reduction.

Chemical reactions The attached oW sheet shows schematically the entirecourse and cycle of the production.

What I claim is:

A cyclic process for preparing sulphur from sulphur dioxide whichcomprises the steps of absorbing sulphur dioxide in an alkali carbonatesolution whereby carbon dioxide gas and an acid alkali sulphite solutionare formed, neutralizing said acid alkali sulphite with alkali carbonateto form carbon dioxide gas and a neutral solution of alkali sulphite,evaporating said neutral alkali sulphite solution, mixing saidevaporated alkali sulphite with carbon and subjecting the mixture toheat to reduce alkali sulphite to alkali sulphide, dissolving saidalkali sulphide and recycling the alkali sulphide solution thus producedto react with carbon dioxide evolved in said steps of absorbing ofsulphur dioxide and neutralizing acid alkali sulphite, whereby hydrogensulphide and alkali carbonate solution are formed, recycling said alkalicarbonate solution to said steps of absorbing sulphur dioxide andneutralizing acid alkali sulphite solution, and reacting said hydrogensulphide with sulphur dioxide to produce elemental sulphur and Water.

GANT GAITHER.

